Living organisms and thermodynamics (Pentcho Valev)

Lukasz Salwinski lukasz at
Thu Oct 16 11:21:19 EST 1997


>   The only contradictory point is whether or not the electrical potential
>extends far from the semipermeable membrane. This can be verified for
>another, even more simplified, system:
>     10 mM  KCl                  M                        1 mM KCl
>where M is a membrane permeable only to K+.
>   For this system thermodynamics says that, at equilibrium, the
>electrical potential difference between points symmetrical with respect
>to but far from the membrane remains constant - 60 mV. However there is
>serious reason to believe that the potential approaches zero with
>distance, in both directions. There has been a discussion in the biophysics
>group on this problem but to no avail.

what about consulting any standard electrochemistry textbook ?
AFAIK concentration cells (and that's what you describe above) 
do work. In fact, if I remember correctly (it was a few years ago) we 
were actually measuring potentials generated in such systems during 
our freshmen biophysics lab. the potentials were measured between bulk 
solutions and were as high as expected. 

sorry to disappoint all the parties involved, but thermodynamics _do_ work

Lukasz Salwinski

ps the discussion here reminds me closely of the prion dispute on do your reading first instead of coming up
   with off the ceiling ideas. it saves time...

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